FPSC lecturer Chemistry bs-17

MCQs Of Chemistry From Past Papers

Q.1. Select the best option/answer and fill in the appropriate box on the Answer Sheet (20)

(i) When an electron is brought from infinite distance close to the nucleus of the atom, the energy of Electron-nucleus system?
(a) increases to a smaller negative value
(b) decreases to a greater negative value
(c) decreases to a smaller positive value
(d) increases to a greater positive value

(ii) The probability of finding the electron in the nucleus is:
(a) 100% due to forces of attraction
(b) finite for all orbitals
(c) Zero for all orbitals
(d) Zero for some orbitals and finite for others

(iii) When Zn metal is kept in CuSO4 solution, copper is precipitated and ZnSO4 is formed because:
(a) Atomic number of Zinc is smaller than copper
(b) Atomic number of Zinc is larger than copper
(c) Standard reduction potential of Zinc is more than that of copper
(d) Standard reduction potential of Zinc is less than that of copper

(iv) Electrolytes when dissolved in water, dissociate into their constituent ions, the degree of dissociation of an electrolyte increases with the:
(a) Presence of a substance yielding common ion
(b) Decreasing temperature
(c) Decreasing concentration of electrolyte
(d) Increasing concentration of electrolyte

(v) There is a large positive entropy change for an exothermic reaction. It means that the reaction will be:
(a) possible at high temperatures only
(b) impossible at all temperatures
(c) possible at low temperatures only
(d) possible at all temperatures

(vi) Which of the following statement is false?
(a) the temperature of the system will fall if an exothermic reaction is isolated from its surroundings
(b) Energy is absorbed when one compound is converted into another with higher heat content
(c) the temperature of the system is likely to fall if heat is absorbed during the course of a reaction
(d) None of these